There is even more to measuring warming than you indicate, and others can point that out. But please get the language right. 'Climate change denialists' is sloppy and misleading language. It is characteristic of climates that they change. No one known to me denies this. The debate is about whether warming has taken place, how much of it there has been, to what extent humans have caused it, and whether or not, if it has occurred, it is dangerous.

No one known to me denies warming has taken place - except perhaps Dr Tim Ball or Dr Bob Carter.

I would agree however, the 'debate' is about how much of it there has been and to what extent humans have caused it. Indeed, this so called 'debate' (in scientific circles) is usually couched in terms of studies in climate sensitivity and attribution. It is very robust.

Whether or not it is dangerous is the reason for the bun-fights between politicians - less so the scientists.

As to the term "Climate change denialists" - perhaps Stephen Kleim is just alluding to those who deny that climate change is, or can be, caused by human activity - and there are quite a few who believe that.

Oh dear! I said that no one known to me denies that climate changes! Yes, no doubt he did mean what you say he meant, but it is sloppy language. Why doesn't he say that some people are sceptical that humans have had much effect on whatever warming has occurred in the last fifty years? If that's what he means. That at least would be clear.

I am agnostic, rather than sceptical, and I have looked hard at the issue over the last three years. I don't think that the underlying measurements are robust at all. They are based on the daily average of the lowest maximum and the highest minimum for the points of record, averaged on a 100 sq km plot, averaged for the planet, and estimated where there are no recording instrument. Why do you think it is robust, let alone valid or reliable? It may be what we have, but it's not robust.

Stephen Keim writes:

“The earth stations which measure temperature do not cover every centimetre of the planet. Hadley leaves such unrepresented areas out of their averaging process. If, for example, the Arctic, which is poorly represented for measuring stations, is warming more quickly than other areas, the Hadley analysis would understate the process of warming.”
“GISS uses a technique (which they have tested for accuracy) which allocates to unmeasured areas the reading of their neighbours. Hence, a different averaging and a different set of results ensue.”

To my untutored eye this seems all very arbitrary. One can easily think of other exclusions.

• For instance all weather stations located above an altitude of 500m.

• All stations where local topography has changed over the years, since local structures may have an “urban heat island effect.”

• All data bases where the number of independent weather stations has been reduced by X% over last fifty years.

Indeed there is no end to the exclusion process.

The weather people should include in their reports an account of all likely errors and assumptions. Further an easily assessable description of their statistical methods and sampling procedures would not be amiss.

The term 'denialist' is used to suggest there's something immoral and an absence of integrity about those dissident voices among scientists who question the orthodoxy of Official Science, and it is used to intimidate others: dare to question the orthodoxy (that human activity is the principal driver of climate warming/change) and you are no better than a denialist. The term has clear meaning in terms of its most common intellectual use in relation to Holocaust denial. It has distant origins in its use by the Inquisition, in similar ways for similar ends.

What is needed is freedom of science in which dissident voices and rigorous debate are encouraged rather than the vilification of dissident scientists as denialists.

qanda: evidence for Bob Carter denying that climate has warmed? My reading suggests that the dissident scientists accept the IPCC estimate of an increase in global temperature over the past 140 years of 0.7 degrees.

The current reviews of procedure on the part of the IPCC and also East Anglia University, arising from Climategate and Glaciergate, will be worthwhile if they result in a return to the principle of open and free scientific inquiry.

The climate scientists all believe we should not be trying to understand their science, and just take their word for things.

They all say different things, they disagree and contradict, when you read what they say on their websites, you are left feeling they are a little oversensitive to questioning or criticism but are not backward in flaming or attacking competitors (and skeptics).

Not a conspiracy, just a common area of interest. If you're a scientist and don't go with the man made contributions to warming theory, well don't expect a grant any time soon, you denying bastard!

The money is for climate research to support Agw or other science areas, the effects of climate on your pet subject, like "Lions in the Serengeti and the effects of climate change on xxxxx" (insert unknown here, try to be original)

If you're a scientist and go along with the Agw theory, you're mainstream, one of the lads and in the team, have a grant, off you go, fine fellow that.

Gosh, is there any incentive there? You don't need a conspiracy, just a mortgage and the usual human nature attraction to conform.

Is it warmer now than ever before, some scientists say yes some say no - both passionately.

Have scientists ever been wrong? Have scientists ever fabricated results, tweaked them a little to get a good result?

Can anyone predict the weather, no, but if their models and science is so good - why can't they?

Because it's complicated.

Yes, we know it's complicated, but why do scientists make absurd statements about climate like, "it's simple physics", well if it's so simple, why can't you predict weather.

Many will pour scorn on this, as weather is considered too complex and too many variables to predict, but climate is simpler for some reason. What?

The community at large hear this strange and alarming contradiction, and put it down to "they just don't have a clue, and attack anyone who questions them" (no reason to deny anything, the scientists supply the fuel for skepticism)

That much, we do know